Wafer level led package and method of fabricating the same

ABSTRACT

Disclosed are a light emitting diode (LED) package and a method of fabricating the same. The LED package includes a first substrate, a semiconductor stack disposed on a front surface of the first substrate, a second substrate including a first lead electrode and a second lead electrode, a plurality of connectors electrically connecting the semiconductor stack to the first and second lead electrodes, and a wavelength converter covering a rear surface of the first substrate. The semiconductor stack includes a first semiconductor layer, a second semiconductor layer, and an active layer disposed between the first semiconductor layer and the second semiconductor layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/359,287, filed on Jan. 26, 2012, and claims priority from and thebenefit of Korean Patent Application No. 10-2011-0008736, filed on Jan.28, 2011, which are hereby incorporated by reference for all purposes asif fully set forth herein.

BACKGROUND

1. Field

Exemplary embodiments of the present invention relate to a lightemitting diode (LED) package and a method of fabricating the same, andmore particularly, to a wafer level LED package and a method offabricating the same.

2. Discussion of the Background

LEDs may be fabricated to be lightweight and slim, and may save energyand have a long lifespan. Accordingly, such LEDs have been widely usedas backlight units for a variety of display devices, including mobilephones. LED packages with LEDs mounted thereon, may realize white lighthaving a high color rendering index. Hence, LEDs have replaced whitelight sources, such as fluorescent lamps, and have been applied togeneral illumination.

Generally, a conventional LED package is fabricated by mountingindividual LED chips on a package having lead electrodes, connecting theLED chips to the lead electrodes using bonding wires, and encapsulatingthe LED chips using an encapsulant.

In such a conventional method of fabricating an LED package, the LEDchips are handled individually. Thus, a lot of time and expense arerequired for the mass production of LED packages, leading to lowerproductivity. Furthermore, since the bonding wires are formed againafter the LED chips are mounted, the process of fabricating the LEDpackage is complicated. In addition, since the wire bonding processusing capillaries requires a space for movement of the capillaries, itacts as a limitation to reducing a package size. Moreover, packagefailure may be frequently caused by a bonding failure or disconnectionof wires.

As a size of a growth substrate for growing an epitaxial layer hasrecently been increased from 2 inches to 4 inches, even up to 6 inches,thousands to ten thousands of LED chips have been fabricated on a singlegrowth substrate. Therefore, there are increasing demands forfabricating LED packages in large quantities and rapidly by using thoseLED chips. However, the prior art has difficulty in meeting theabove-described demands.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form any part of theprior art nor what the prior art may suggest to a person of ordinaryskill in the art.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention provide an LED package,which is suitable for mass production through a simplified process, anda method of fabricating the same.

Exemplary embodiments of the present invention also provide an LEDpackage, which is suitable for miniaturization, and a method offabricating the same.

Exemplary embodiments of the present invention also provide an LEDpackage, which is structurally stable, and a method of fabricating thesame.

Exemplary embodiments of the present invention also provide an LEDpackage, which is suitable for realizing mixed color light, particularlywhite light, and a method of fabricating the same.

Additional features of the invention will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention.

An exemplary embodiment of the present invention provides a method offabricating an LED package. The method includes forming a plurality ofsemiconductor stacks on a first substrate, each of the semiconductorstacks comprising a first semiconductor layer, a second semiconductorlayer, and an active region disposed between the first semiconductorlayer and the second semiconductor layer; coupling the plurality ofsemiconductor stacks to a second substrate, the second substratecomprising first lead electrodes and second lead electrodes arrangedcorresponding to the plurality of semiconductor stacks; and cutting thefirst substrate and the second substrate into a plurality of packagesafter the coupling is completed.

Another exemplary embodiment of the present invention provides a waferlevel LED package. The wafer level LED package includes a firstsubstrate; a semiconductor stack disposed on a front surface of thefirst substrate, the semiconductor stack comprising a firstsemiconductor layer, a second semiconductor layer, and an active layerdisposed between the first semiconductor layer and the secondsemiconductor layer; a second substrate comprising a first leadelectrode and a second lead electrode; a plurality of connectorselectrically connecting the semiconductor stack to the first and secondlead electrodes; and a wavelength converter covering a rear surface ofthe first substrate.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, and FIG. 7 arecross-sectional views illustrating a method of fabricating an LEDpackage according to an exemplary embodiment of the present invention.

FIG. 8, FIG. 9, FIG. 10, FIG. 11, and FIG. 12 are cross-sectional viewsillustrating a method of fabricating an LED package according to anotherexemplary embodiment of the present invention.

FIG. 13, FIG. 14, FIG. 15, and FIG. 16 are cross-sectional viewsillustrating a method of fabricating an LED package according to anotherexemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Exemplary embodiments of the present invention will be described belowin detail with reference to the accompanying drawings. These embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the invention to those skilled in theart. The invention may, however, be embodied in many different forms andshould not be construed as being limited to the embodiments set forthherein. In the drawings, the widths, lengths and thicknesses of elementsmay be exaggerated for clarity. Throughout the drawings and writtendescription, like reference numerals will be used to refer to likeelements.

It will be understood that when an element, such as a layer, a region,or a substrate, is referred to as being “on,” “connected to,” or“coupled to” another element, it may be directly on, connected orcoupled to the other element, or intervening elements may be present. Incontrast, when an element or layer is referred to as being “directlyon,” “directly connected to,” or “directly coupled to,” another element,there are no intervening elements present. It will be understood thatfor the purposes of this disclosure, “at least one of X, Y, and Z” canbe construed as X only, Y only, Z only, or any combination of two ormore items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ).

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

FIGS. 1 to 7 are cross-sectional views illustrating a method offabricating an LED package according to an exemplary embodiment of thepresent invention.

(Preparation of Wafer 20)

Referring to FIG. 1, a wafer 20, in which a plurality of semiconductorstacks 30 are formed on a first substrate 21, is prepared.

The wafer 20 includes the first substrate 21, and the plurality ofsemiconductor stacks 30 arranged on the first substrate 21. In addition,the wafer 20 may further include an ohmic contact layer 31, aninsulation layer 33, first electrodes 36 a, second electrodes 36 b, anunderfill 40 a, and a buffer layer (not shown). Each of thesemiconductor stacks 30 may include a first-conductivity-typesemiconductor layer 25, an active layer 27, and asecond-conductivity-type semiconductor layer 29. In addition, each firstelectrode 36 a may include a first electrode pad 35 a and a first bump37 a, and each second electrode 36 b may include a second electrode pad35 b and a second bump 37 b.

The first substrate 21 may be a growth substrate capable of growing anitride semiconductor layer. For example, the first substrate 21 may bea sapphire substrate, a silicon carbide substrate, or a spinelsubstrate. The first substrate 21 is a transparent substrate capable oftransmitting light.

The semiconductor stacks 30 may be fabricated through a typical LED chipfabricating process. That is, epitaxial layers, which include thefirst-conductivity-type semiconductor layer 25, the active layer 27, andthe second-conductivity-type semiconductor layer 29, are grown on thefirst substrate 21 and are patterned to form the plurality ofsemiconductor stacks 30 on the first substrate 21. In order to expose aportion of the first-conductivity-type semiconductor layer 25, thesecond-conductivity-type semiconductor layer 29 and the active layer 27may also be partially removed.

The active layer 27, the first-conductivity-type semiconductor layer 25,and the second-conductivity-type semiconductor layer 29 may be formed ofgroup III-N compound semiconductors, for example, (Al, Ga, In)Nsemiconductors. The first-conductivity-type semiconductor layer 25 andthe second-conductivity-type semiconductor layer 29 may each be singlelayer or multiple-layer. For example, the first-conductivity-typesemiconductor layer 25 and/or the second-conductivity-type semiconductorlayer 29 may include a contact layer and a clad layer. In addition, thefirst-conductivity-type semiconductor layer 25 and/or thesecond-conductivity-type semiconductor layer 29 may include asuperlattice layer. Moreover, the active layer 27 may have a singlequantum well structure or a multiple quantum well structure. Forexample, the first conductivity type may be an n type and the secondconductivity type may be a p type; however, the invention is not limitedthereto. The first conductivity type may be a p type and the secondconductivity type may be an n type. The buffer layer (not shown)alleviates a lattice mismatch between the first substrate 21 and thefirst-conductivity-type semiconductor layer 25, leading to a reductionin defect density occurring within the semiconductor layers 25, 27, and29.

Meanwhile, the ohmic contact layer 31 may be formed on thesecond-conductivity-type semiconductor layer 29. The first electrode pad35 a and the second electrode pad 35 b may be formed on thefirst-conductivity-type semiconductor layer 25 and thesecond-conductivity-type semiconductor layer 29, respectively. Forexample, the ohmic contact layer 31 may include a transparent conductivelayer, such as Ni/Au, indium tin oxide (ITO), indium zinc oxide (IZO),or ZnO; however, the invention is not limited thereto. The ohmic contactlayer 31 may include a reflective metal layer. The first electrode pad35 a and the second electrode pad 35 b may include one or more materialsselected from Ti, Cu, Ni, Al, Au, and Cr. The second electrode pad 35 bmay be electrically connected to the second-conductivity-typesemiconductor layer 29 through the ohmic contact layer 31. Before thefirst and second electrode pads 35 a and 35 b are formed, the insulationlayer 33 covering the semiconductor stacks 30 may also be formed. Theinsulation layer 33 may be formed of silicon oxide or silicon nitride.

Furthermore, the first bump 37 a and the second bump 37 b may be formedon the first electrode pad 35 a and the second electrode pad 35 b,respectively. The first bump 37 a and the second bump 37 b areconnectors that electrically connect the plurality of semiconductorstacks 30 to a first lead electrode 53 a and a second lead electrode 53b of a second substrate 51. The first bump 37 a and the second bump 37 bstructurally connect the plurality of semiconductor stacks 30 to thesecond substrate 51.

The first bump 37 a and the second bump 37 b may be formed of Au or asolder. Alternatively, after a bump is formed of a rigid metal such asNi or Ni alloy, Au or a solder may be formed on the bump. In addition,the first bump 37 a and the second bump 37 b may be formed of a studbump using a wire bonding technique.

Meanwhile, the underfill 40 a may be formed on the first substrate 21,on which the semiconductor stacks 30 are formed. The underfill 40 a maybe formed of a thermosetting resin or a thermoplastic resin. Inaddition, the underfill 40 a may include a phosphor and/or a filler. Thephosphor may be added for converting a wavelength of light emittedtoward the lateral sides of the semiconductor stacks 30, and the fillermay be added for adjusting a coefficient of thermal expansion and amodulus of elasticity of the underfill 40 a. For example, the underfill40 a may be formed using a spin coating or lamination technique. Forexample, the underfill 40 a may be formed using a screen printingtechnique employing a squeeze. Accordingly, the underfill 40 a may beformed to cover the lateral sides and the top surfaces of thesemiconductor stacks 30. The first and second bumps 37 a and 37 b maypass through the underfill 40 a and be exposed to the outside.

The underfill 40 a may be cured in the step of preparing the wafer 20;however, the invention is not limited thereto. The underfill 40 a mayremain in a B-stage state in the step of preparing the wafer 20.Thereafter, while bonding the first and second bumps 37 a and 37 b tothe lead electrodes 53 a and 53 b of the second substrate 21, theB-stage underfill 40 a may be cured.

(Preparation of Package Member 50)

Referring to FIG. 2, the second substrate 51 including the first leadelectrodes 53 a and the second lead electrodes 53 b is prepared as apackage member 50.

The second substrate 51 may be a printed circuit board (PCB) on whichthe lead electrodes 53 a and 53 b are printed. For example, the secondsubstrate 51 may be an organic PCB such as an FR4 PCB, a metal PCB, ametal core PCB, a ceramic substrate, a Si substrate, an AlN substrate,or a SiC substrate.

In a case where the second substrate 51 is a conductive substrate suchas a metal PCB, the lead electrodes 53 a and 53 b may be insulated fromthe conductive substrate by an insulation layer (not shown).

The first and second lead electrodes 53 a and 53 b may have internalterminals or pads on the second substrate 51, and may have externalterminals under the second substrate 51 in order for connection to anexternal power supply. The first and second lead electrodes 53 a and 53b pass through the second substrate 51. The first and second leadelectrodes 53 a and 53 b may fill through-holes of the second substrate51; however, the invention is not limited thereto. The first and secondlead electrodes 53 a and 53 b may be formed along the lateral sides ofthe through-holes.

(Coupling of Wafer 20 and Package Member 50)

Referring to FIG. 3, the first bumps 37 a and the second bumps 37 b arebonded to the first lead electrodes 53 a and the second lead electrodes53 b, respectively. The first and second bumps 37 a and 37 b may bebonded to the first and second lead electrodes 53 a and 53 b using abonding technique, such as a thermocompression bonding, a thermosonicbonding, or a reflow. For the bonding, metal pads such as Au may beformed on the second substrate 51. In addition, a solder paste may beadditionally formed on the metal pads.

Meanwhile, for example, in a case where the first and second bumps 37 aand 37 b are bonded by a thermocompression bonding, a temperatureprofile of a thermocompression bonding process may be adjusted to reducea viscosity of the B-stage underfill 40 a when a metal bonding is inprogress, causing the B-stage underfill 40 a to flow. Thereafter, whilea temperature is maintained or decreased, a process of curing theB-stage underfill 40 a may be carried out. Accordingly, the underfill 40a may reinforce the coupling of the wafer 20 and the package member 50.Furthermore, the filler may be added to the underfill 40 a, so that theunderfill 40 a can reduce a difference in coefficient of thermalexpansion between the wafer 20 and the package member 50. Therefore, theunderfill 40 a may improve the structural stability and reliability ofthe LED package.

Meanwhile, after the coupling, a rear surface of the first substrate 21may be partially removed by grinding, and thus, the first substrate 21may become thin.

(Formation of Wavelength Converter 60)

Referring to FIG. 4, after the coupling process is completed, awavelength converter 60 is formed on the rear surface of the firstsubstrate 21. The wavelength converter 60 may be formed by coating aphosphor or a phosphor-containing resin. For example, thephosphor-containing resin may be coated on the first substrate 21, andthe wavelength converter 60 may be formed at a uniform thickness using asqueeze. Alternatively, a phosphor-containing wavelength converter, forexample, a glass, may be attached to the first substrate 21. The glassmay be attached to the first substrate 21 using an adhesive. Also, theglass may be attached to the first substrate 21 using a low-temperaturedirect bonding technique, without using an adhesive.

(Cutting Process)

Referring to FIG. 5, the first substrate 21 and the second substrate 51are cut. In a case where the underfill 40 a is formed, the underfill 40a is also cut. The first substrate 21 and the second substrate 51 may becut by scribing, braking, sawing, grinding, or laser. As a result, thefabrication of individual LED packages is completed.

The first substrate 21 and the second substrate 51 may be cut using alaser in the same process. Accordingly, the first substrate 21 and thesecond substrate 51 may be formed to have substantially the same size;however, the invention is not limited thereto. After the first substrate21 is cut, the second substrate 51 may be cut through a separateprocess. In this case, as illustrated in FIG. 5, the first substrate 21may be slightly smaller in size than the second substrate 51.

Meanwhile, phosphor characteristics of the phosphor-containingwavelength converter 60 are easily changed by moisture penetrated fromthe outside. In particular, in a case where the wavelength converter 60is formed of a silicone resin, it is necessary to protect the siliconeresin and the phosphor from moisture penetrated from the outside. Tothis end, as illustrated in FIG. 6, a moisture barrier coating 70 may beformed to cover the wavelength converter 60.

Before the cutting of the first substrate 21, the moisture barriercoating 70 may be formed on the first substrate 21 to cover thewavelength converter 60. Thereafter, the moisture barrier coating 70 maybe cut together with the first substrate 21. Alternatively, the moisturebarrier coating 70 may be formed after the cutting of the firstsubstrate 21 and the underfill 40 a, or may be formed after the cuttingof the second substrate 51. Therefore, the moisture barrier coating 70covers the wavelength converter 60 and the lateral side of the underfill40 a, thereby preventing moisture from penetrating from the outside intothe LED package.

For example, the moisture barrier coating 70 may include a silicon oxidefilm or a silicon nitride film. As illustrated in FIG. 7, the moisturebarrier coating 70 may be formed by alternately laminating an organicmaterial layer 71 and an inorganic material layer 73. For example, themoisture barrier coating 70 may be formed by alternately laminating atransparent polymer and an oxide or nitride of a metal such as silicon(Si) or aluminum (Al) using a low-temperature vacuum deposition. Themoisture barrier coating 70 lengthens a moisture penetration path toprevent moisture from penetrating into the wavelength converter 60.

According to this exemplary embodiment, since the plurality ofsemiconductor stacks 30 are mounted on the package member 50 at a waferlevel, a fabrication process may be simplified and a fabrication costmay be reduced, as compared to a conventional fabricating process whichmounts individual chips. Furthermore, in a package fabricating processaccording to the exemplary embodiment, it is unnecessary to electricallyconnect the lead electrodes to the semiconductor stacks using bondingwires. Therefore, it may be possible to avoid a package failure causedby breakage or shorting of bonding wires.

Although it has been described above that the underfill 40 a is formedto cover the plurality of semiconductor stacks 30 before the bonding ofthe wafer 20 and the package member 50, the underfill 40 a may not beneeded in all aspects. Moreover, after the coupling of the wafer 20 andthe package member 50, the underfill 40 a may be formed by injecting anunderfill material into a gap between the first substrate 21 and thesecond substrate 51.

FIGS. 8 to 12 are cross-sectional views illustrating a method offabricating an LED package according to another exemplary embodiment ofthe present invention.

Referring to FIG. 8, a wafer 20 and a package member 50 are prepared andcoupled to each other, as described above with reference to FIGS. 1 to3. Thereafter, a surface texture T is formed on a rear surface of thefirst substrate 21. The surface texture T may be formed by etching thefirst substrate 21 using wet etching, electron beam lithography, or nanoimplant technique. For example, the surface texture T may be formed withpatterns having a pitch ranging from tens of namometers to severalmicrometers and having an aspect ratio of 1 or more. The surface textureT may improve a light extraction efficiency of light emitted from thesemiconductor stacks 30.

Referring to FIG. 9, the first substrate 21 is cut. The first substrate21 may be cut to have an inverted triangular cross-section by using adiamond blade or a laser. Therefore, as illustrated in FIG. 9, in thecut region, the lateral side of the first substrate 21 may be formed tobe inclined with respect to a vertical direction of the rear surface ofthe first substrate 21. The inclined lateral side of the first substrate21 may improve a light extraction efficiency of light emitted from thesemiconductor stacks 30.

Meanwhile, an underfill 40 a under the cut region may be partiallyremoved. The underfill 40 a may be removed such that a portion thereofremains on the second substrate 51; however, the invention is notlimited thereto. The underfill 40 a may be removed such that the surfaceof the second substrate 51 is exposed.

Referring to FIG. 10, a wavelength converter 60 a covering the firstsubstrate 21 is formed. The wavelength converter 60 a may be formed of aphosphor-containing resin. The wavelength converter 60 a covers the rearsurface and the lateral side of the first substrate 21, and also coversthe lateral side of the underfill 40 a exposed within the cut region.

Referring to FIG. 11, the second substrate 21 is cut, and therefore, thefabrication of individual LED packages is completed. The wavelengthconverter 60 a and the remaining underfill 40 a under the cut region mayalso be cut.

Referring to FIG. 12, a moisture barrier coating 70 may be additionallyformed for preventing moisture from penetrating into the wavelengthconverter 60 a, as described above with reference to FIG. 6. Forexample, the moisture barrier coating 70 may be formed after the removalof the wavelength converter 60 a and the remaining underfill 40 a underthe cut region. The moisture barrier coating 70 may be formed before orafter the cutting of the second substrate 51.

According to this exemplary embodiment, the light extraction efficiencymay be improved by forming the surface texture T on the rear surface ofthe first substrate 21. In addition, the light extraction efficiency maybe further improved by cutting the first substrate 21 such that thelateral side of the first substrate 21 is inclined. The technique forforming the surface texture T and forming the inclined lateral side isnot limited to this embodiment, but may be equally applied to otherembodiments.

Meanwhile, in this exemplary embodiment, since the wavelength converter60 a is formed after the partial removal of the first substrate 21 andthe underfill 40 a, the wavelength converter 60 a may be formed to coverthe lateral sides of the semiconductor stacks 30.

FIGS. 13 to 16 are cross-sectional views illustrating a method offabricating an LED package according to another exemplary embodiment ofthe present invention.

Referring to FIG. 13, after the wafer 20 is coupled to the packagemember 50, the surface texture T is formed on the rear surface of thefirst substrate 21, and the first substrate 21 is cut such that thelateral side thereof is inclined, as described above with reference toFIGS. 8 and 9. However, in this embodiment, the process of forming theunderfill 40 a in the wafer preparing step is skipped, as opposed to theprevious exemplary embodiments.

Referring to FIG. 14, a wavelength converter 60 b covering the cut firstsubstrate 21 is formed. In addition, the wavelength converter 60 b mayfill a gap between the first substrate 21 and the second substrate 51.That is, the underfill 40 a may also be formed using the wavelengthconverter 60 b. The wavelength converter 60 b may be formed of aphosphor-containing resin. Alternatively, the wavelength converter 60 bmay be formed on the first substrate 21 at a uniform thickness by usinga squeeze.

Referring to FIG. 15, the second substrate 51 is cut, and therefore, thefabrication of individual LED packages is completed. The wavelengthconverter 60 b disposed within the cut region of the first substrate 21may also be cut.

Referring to FIG. 16, a moisture barrier coating 70 may be additionallyformed for preventing moisture from penetrating into the wavelengthconverter 60 b, as described above with reference to FIG. 6. Forexample, after the wavelength converter 60 b under the cut region isremoved, the moisture barrier coating 70 may be formed to cover thewavelength converter 60 b. The moisture barrier coating 70 may be formedbefore or after the cutting of the second substrate 51.

According to the exemplary embodiments of the present invention, theplurality of semiconductor stacks formed on the first substrate arecoupled to the second substrate at a wafer level, and the firstsubstrate and the second substrate are cut to fabricate the LEDpackages. Therefore, the chip bonding process may be simplified and theworking time may be considerably reduced. Furthermore, since the LEDpackages are fabricated at a wafer level, it is suitable for packageminiaturization. Moreover, the underfill may improve the bonding forceof the first substrate and the second substrate. Therefore, thestructurally stable LED packages may be provided. By forming themoisture barrier layer, it may be possible to prevent moisture frompenetrating from the outside into the LED package.

In addition, mixed color light, particularly white light, may berealized using the wavelength converter. Using the underfill and/or thewavelength converter, the wavelength conversion may be performed onlight emitted toward the lateral sides and bottom surfaces of thesemiconductor stack, as well as the top surfaces thereof.

While the exemplary embodiments of the present invention have beendescribed with reference to the specific embodiments, it will beapparent to those skilled in the art that various changes andmodifications may be made without departing from the spirit and scope ofthe invention. Thus, it is intended that the present invention cover themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

What is claimed is:
 1. A light emitting diode (LED) package, comprising:a first substrate; a semiconductor stack disposed on a front surface ofthe first substrate, the semiconductor stack comprising a firstsemiconductor layer, a second semiconductor layer, and an active layerdisposed between the first semiconductor layer and the secondsemiconductor layer; a second substrate comprising a first leadelectrode and a second lead electrode; a plurality of connectorselectrically connecting the semiconductor stack to the first and secondlead electrodes; and a wavelength converter covering a rear surface ofthe first substrate.
 2. The LED package of claim 1, further comprising:an underfill disposed between the first substrate and the secondsubstrate.
 3. The LED package of claim 2, wherein the underfillcomprises at least one of a phosphor and a filler.
 4. The LED package ofclaim 2, wherein the wavelength converter covers at least a portion of alateral side of the underfill.
 5. The LED package of claim 4, furthercomprising: a moisture barrier coating covering the wavelengthconverter.
 6. The LED package of claim 5, wherein the moisture barriercoating covers a lateral side of the underfill.
 7. The LED package ofclaim 1, further comprising: a moisture barrier coating covering thewavelength converter.
 8. The LED package of claim 7, wherein themoisture barrier coating comprises an organic material layer and aninorganic material layer alternately laminated.
 9. The LED package ofclaim 7, wherein the wavelength converter fills a gap between the firstsubstrate and the second substrate.
 10. The LED package of claim 1,wherein the wavelength converter comprises a phosphor-containing glass.11. The LED package of claim 10, wherein the glass is directly on therear surface of the first substrate.
 12. The LED package of claim 1,wherein a rear surface of the first substrate is textured.
 13. The LEDpackage of claim 1, wherein a lateral side of the first substrate isinclined with respect to a vertical direction of the rear surface of thefirst substrate.